JP6016088B2 - Shutter mechanism and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus using an electrophotographic method such as a copying machine, a printer, a facsimile, or a multifunction machine thereof, and a shutter mechanism in a powder supply device installed therein.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a toner replenishing device (powder replenishing device) containing toner (one-component developer) is appropriately moved toward a developing device containing two-component developer. Techniques for supplying toner are known (see, for example, Patent Documents 1 and 2).

  In a developing device using a two-component developer, toner is appropriately replenished from the toner replenishing device into the developing device through a toner replenishing port provided in the developing device in accordance with toner consumption in the developing device. The replenished toner is agitated and mixed together with the developer in the developing device by a conveying member (agitating member) such as a conveying screw. Part of the stirred and mixed developer is supplied to a developing roller (developer carrier). The developer carried on the developing roller is regulated to an appropriate amount by a doctor blade (developer regulating member), and then the toner in the two-component developer is located at a position facing the photoreceptor drum (image carrier). A toner image (image) is formed on the photosensitive drum by adhering to the latent image on the drum.

In such an image forming apparatus, the developing device is detachably formed, and a shutter member (shutter) that opens and closes a discharge port (toner flow path) of the toner replenishing device in conjunction with the attaching / detaching operation of the developing device is installed. Has been.
Specifically, when the developing device is attached to the main body of the image forming apparatus, the shutter member of the toner replenishing device installed in the main body of the image forming apparatus is pushed by the developing device, and the shutter member moves to a position where the discharge port is opened. As a result, the toner replenishing device and the developing device communicate with each other, and toner replenishment from the toner replenishing device to the developing device becomes possible. On the other hand, when the developing device is detached from the image forming apparatus main body, the shutter member is urged by a spring installed in the image forming apparatus main body, and the shutter member moves to a position for closing the discharge port. Toner leakage from the discharge port of the toner supply device is prevented.

  On the other hand, in Patent Documents 1 and 2, for the purpose of preventing toner scattering in the vicinity of the shutter member, shutter holding for guiding the movement of the shutter member in the opening / closing direction to the discharge port (toner flow path) of the toner replenishing device. A technique is disclosed in which a discharge port is opened and closed by forming a portion (insertion port) and fitting the shutter member in a state in which the shutter member is elastically deformed.

  The above-described image forming apparatuses disclosed in Patent Documents 1 and 2 are molded when a shutter holding portion (insertion port) is molded from a resin material using a mold for the purpose of reducing the weight and cost of the apparatus. The distance of the wall (groove) of the shutter holding portion formed so as to sandwich the shutter member due to the draft angle of the shutter corresponds to the front end portion in the opening direction compared to the portion corresponding to the rear end portion in the opening direction of the shutter member. There was a possibility that the part to be widened. In such a case, a gap (or a portion with a low degree of fitting) between the shutter member in a state where the discharge port of the shutter holding portion is opened and the wall portion (groove portion) of the shutter holding portion. May occur, and the toner may scatter from that portion.

  Such a problem is not limited to the shutter mechanism installed in the toner replenishing device (powder replenishing device) in which toner (one-component developer) is accommodated, but other powders (for example, two-component) This is common to all shutter mechanisms provided with a shutter member that opens and closes a discharge port through which the developer is discharged.

  The present invention has been made to solve the above-described problems, and a shutter mechanism that reduces a problem in which a gap is generated between the shutter member and the shutter holding portion to cause powder scattering, and An object is to provide an image forming apparatus.

According to a first aspect of the present invention, there is provided a shutter mechanism comprising: a shutter member that opens and closes a discharge port from which powder is discharged; the discharge port is formed so as to face the surface of the shutter member; A shutter holding portion that is formed so as to face both ends in the width direction of the shutter member, and that guides the shutter member while holding the shutter member so that the shutter member moves in the opening and closing direction. member is formed to move in a direction to open the discharge port in a state where the shutter member is relatively inclined with respect to the wall portion of the shutter holding portion in a plane which is opened and closed, the shutter holding portion The wall portion is formed so as to be inclined with respect to the opening / closing direction of the shutter member in a plane where the shutter member is opened / closed .

  In the present invention, since the shutter member moves in the opening direction in a state where the shutter member is inclined relative to the wall portion of the shutter holding portion, a gap is generated between the shutter member and the shutter holding portion, and powder scattering occurs. It is possible to provide a shutter mechanism and an image forming apparatus that can reduce defects.

1 is an overall configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view showing the vicinity of a process cartridge installed in the image forming apparatus of FIG. 1. It is an enlarged view which shows a developing device. It is sectional drawing which looked at the circulation path in a developing device to the longitudinal direction. It is a schematic sectional drawing which shows the Y1-Y1 cross section in the circulation path | route of FIG. It is a schematic sectional drawing which shows the Y2-Y2 cross section in the circulation path | route of FIG. FIG. 3 is a configuration diagram illustrating a toner supply device. FIG. 3 is a cross-sectional view of the toner replenishing device as viewed in the longitudinal direction. In a shutter mechanism, it is (A) the figure which shows the state which closed the discharge port, and (B) the figure which shows the state in which the shutter member opened the discharge port. (A) The figure which shows the state by which the sealing member was installed in the shutter member of FIG. 9 (A), and (B) Sectional drawing which shows the RR cross section. In another form of the shutter mechanism, (A) a diagram showing a state where the shutter member closes the discharge port, and (B) a diagram showing a state where the shutter member opens the discharge port.

Embodiment.
Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

First, the configuration and operation of the entire image forming apparatus in the embodiment will be described with reference to FIG.
The writing units 2A to 2D are devices for writing an electrostatic latent image on the photosensitive drum 21 (image carrier) after the charging process based on image information. The writing units 2A to 2D are optical scanning devices using polygon mirrors 3A to 3D, optical elements 4A to 4D, and the like. An LED array can be used as the writing unit instead of the optical scanning device.
The paper feed unit 61 stores a transfer material P such as recording paper or OHP, and feeds the transfer material P toward the transfer belt 30 during image formation.

The transfer belt 30 is an endless belt for transferring the toner image formed on the photosensitive drum 21 onto the transfer material P by electrostatically attracting and transferring the transfer material P to the surface thereof. A suction roller 64 and a belt cleaner 65 are provided on the outer peripheral surface.
The transfer roller 24 that faces the photosensitive drum 21 via the transfer belt 30 includes a cored bar and a conductive elastic layer that covers the cored bar. The conductive elastic layer of the transfer roller 24 is prepared by blending and dispersing a conductive agent such as carbon black, zinc oxide or tin oxide in an elastic material such as polyurethane rubber or ethylene-propylene-diene polyethylene (EPDM). It is an elastic body whose (volume resistivity) is adjusted to medium resistance.

The fixing unit 66 includes a heating roller 68 and a pressure roller 67 and fixes the toner image on the transfer material P to the transfer material P by pressure and heat.
The four process cartridges 20Y, 20C, 20M, and 20BK arranged in the vertical direction along the transfer belt 30 are for forming toner images of yellow, cyan, magenta, and black, respectively.

On each of the process cartridges 20Y, 20C, 20M, and 20BK, a carrier (magnetic carrier) and toner (toner particles) of each color (yellow, cyan, magenta, black) are transferred to the developing device 23 via the powder supply device 80. Agent cartridges 28Y, 28C, 28M, and 28BK for supply are installed.
The process cartridges 20Y, 20C, 20M, and 20BK and the agent cartridges 28Y, 28C, 28M, and 28BK can be attached to and detached from the apparatus main body 1 by opening the transfer belt 30 around the rotation support shaft (left and right in FIG. 1). It is a detaching operation by moving the direction).

  The image forming apparatus according to the present embodiment is a composite image forming apparatus that functions as a copying machine and a printer. When functioning as a copying machine, the image information read from the scanner is subjected to various image processing such as A / D conversion, MTF correction, gradation processing, etc., and converted into writing data. In the case of functioning as a printer, image processing is performed on image information in a format such as a page description language or a bitmap transmitted from a computer or the like, and converted into write data.

  At the time of image formation, exposure light corresponding to the image information of black, magenta, cyan, and yellow is irradiated from the writing units 2A to 2D to the process cartridges 20BK, 20M, 20C, and 20Y, respectively. That is, exposure light (laser light) emitted from each light source passes through the polygon mirrors 3A to 3D, the optical elements 4A to 4D, and is irradiated onto each photosensitive drum 21. Thus, a toner image corresponding to the exposure light is formed on the photosensitive drum 21 (image carrier) of each process cartridge 20BK, 20M, 20C, 20Y. The toner image is transferred to the transfer material P.

  The material P to be transferred fed from the paper feeding unit 61 is conveyed to the position of the transfer belt 30 at the timing of the registration roller 63 (timing roller). The suction roller 64 disposed at the feeding position of the transfer belt 30 causes the transfer belt 30 to suck the material to be transferred P fed by voltage application. As the transfer belt 30 travels in the direction of the arrow, the transfer material P moves sequentially through the positions of the process cartridges 20Y, 20C, 20M, and 20BK, and the toner images of the respective colors are superimposed and transferred.

  The material P to which the color toner image is transferred is separated from the transfer belt 30 and reaches the fixing unit 66. The toner image on the transfer material P is fixed on the transfer material P by being heated while being sandwiched between the heating roller 68 and the pressure roller 67. On the other hand, the surface of the transfer belt 30 after the transfer material P is separated reaches the position of the belt cleaner 65, and dirt such as toner adhering to the surface is cleaned.

Next, the process cartridge and the agent cartridge in the image forming apparatus will be described in detail.
The process cartridges 20Y, 20C, 20M, and 20BK have substantially the same structure, and the agent cartridges 28Y, 28C, 28M, and 28BK and the powder replenishing device 80 have substantially the same structure. The cartridge, the agent cartridge, and the powder replenishing device are illustrated by removing the alphabet (Y, C, M, BK). In addition, the writing unit is illustrated by removing the alphabet (A to D).

  FIG. 2 is an enlarged view showing the vicinity of the process cartridge 20 installed in the apparatus main body 1. FIG. 3 is an enlarged view showing the developing device 23 installed in the process cartridge 20. 4 is a cross-sectional view of the circulation path in the developing device 23 as viewed from the direction of the arrow X shown in FIG. FIG. 5 is a cross-sectional view showing a Y1-Y1 cross section of the circulation path in the developing device 23 of FIG. 6 is a cross-sectional view showing a Y2-Y2 cross section of the circulation path in the developing device 23 of FIG.

As shown in FIG. 2, the process cartridge 20 includes a photosensitive drum 21 as an image carrier, a charging unit 22, a developing device 23 (developing unit), and a cleaning unit 25, and is a premix developing unit. System (development system in which carrier is replenished / discharged as appropriate) is adopted.
The photosensitive drum 21 as an image carrier is a negatively charged organic photosensitive member, and is rotationally driven counterclockwise by a rotation driving mechanism (not shown).

The charging unit 22 is a charging roller having elasticity, in which a medium-resistance foamed urethane layer in which a urethane resin, carbon black as conductive particles, a sulfurizing agent, a foaming agent, and the like are formed in a roller shape on a core metal. The material of the middle resistance layer of the charging unit 22 is urethane, ethylene-propylene-diene polyethylene (EPDM), butadiene acrylonitrile rubber (NBR), silicone rubber, isoprene rubber, etc. It is also possible to use a rubber material in which a conductive material such as the above is dispersed or a foamed material of these materials.
The cleaning unit 25 is provided with a cleaning brush (or cleaning blade) that is in sliding contact with the photosensitive drum 21, and mechanically removes and collects untransferred toner on the photosensitive drum 21.

  In the developing device 23, two developing rollers 23a1 and 23a2 as developer carrying members are disposed so as to be close to the photosensitive drum 21, and the photosensitive drum 21 and the magnetic brush are in contact with each other at both opposing portions. A development area is formed. In the developing device 23, a developer G (two-component developer) as a powder composed of toner T and carrier C is accommodated. The developing device 23 develops the electrostatic latent image formed on the photosensitive drum 21 (forms a toner image). The configuration and operation of the developing device 23 will be described in detail later.

Here, the developing device 23 in the present embodiment is of a premix developing system, and a new carrier C (developer G) is appropriately fed from the agent cartridge 28 to the powder replenishing device 80 ( In addition, the deteriorated developer G is discharged toward the agent storage container 70 installed outside the developing device 23.
Referring to FIG. 2, the agent cartridge 28 accommodates developer G (toner T and carrier C) as powder supplied into the developing device 23 therein. The agent cartridge 28 functions as a toner cartridge that supplies new toner T to the developing device 23 and also functions as a carrier cartridge that supplies new carrier C to the developing device 23. Specifically, powder replenishment is performed based on information on the toner concentration (which is the ratio of toner in the developer G) detected by a magnetic sensor 26 (see FIG. 4) installed in the developing device 23. The device 80 (the replenishing screw 84 and the stirring member 83) is driven, and the developer G is directed from the powder replenishing device 80 (the developer G supplied from the agent cartridge 28 is stored) toward the developing device 23. Is supplied as appropriate.
In the present embodiment, the mixing ratio (toner concentration) of the toner T with respect to the carrier C in the developer G of the agent cartridge 28 is set to be relatively high.

The powder replenishing device 80 temporarily stores the developer G (toner T and carrier C) supplied from the agent cartridge 28 via the supply pipe 29, and according to the consumption of the toner T in the developing device 23. It is for guiding into the developing device 23.
The configuration and operation of the powder supply device 80 will be described in detail later with reference to FIGS.

Next, an image forming process performed on the photosensitive drum 21 will be described.
Referring to FIG. 2, when the photosensitive drum 21 is driven to rotate counterclockwise, first, the surface of the photosensitive drum 21 is uniformly charged at the position of the charging unit 22. Thereafter, the surface of the charged photosensitive drum 21 reaches the irradiation position of the exposure light L, and an exposure process by the writing unit 2 is performed. That is, by selectively removing the charge on the photosensitive drum 21 in accordance with the image information by irradiation with the exposure light L, a difference (potential contrast) from the potential of the non-image portion that has not been irradiated is generated, and electrostatic latent Form an image. In this exposure step, the charge generation material receives light in the photosensitive layer of the photosensitive drum 21 to generate charges, and among these holes, the holes cancel out the charged charges on the surface of the photosensitive drum 21.

Thereafter, the surface of the photosensitive drum 21 on which the latent image is formed reaches a position facing the developing device 23. The electrostatic latent image on the photosensitive drum 21 comes into contact with the magnetic brush on the developing rollers 23a1 and 23a2, and the negatively charged toner T in the magnetic brush is attached and visualized.
Specifically, the developer G pumped up by the magnetic force generated by the magnetic pole of the upper developing roller 23a1 is made into an appropriate amount by a doctor blade 23c as a developer regulating member, and then the developing region (the developing region (opposite part to the photosensitive drum 21)). This is a region where the two developing rollers 23a1 and 23a2 and the photosensitive drum 21 face each other). The carrier C spiked in the development area rubs the photosensitive drum 21. At this time, the toner T mixed with the carrier C is negatively charged due to friction with the carrier C. On the other hand, the carrier C is positively charged. A predetermined developing bias is applied to the developing rollers 23a1 and 23a2 from a power supply unit (not shown). As a result, an electric field is formed between the developing rollers 23a1 and 23a2 and the photosensitive drum 21, and the negatively charged toner T is selectively attached only to the image portion on the photosensitive drum 21 by the electric field, and the toner image. Form.

Thereafter, the surface of the photosensitive drum 21 on which the toner image is formed reaches a position facing the transfer belt 30 and the transfer roller 24. Then, the toner image on the photosensitive drum 21 is transferred onto the transfer material P conveyed to the opposite position in accordance with this timing. At this time, a predetermined voltage is applied to the transfer roller 24.
Thereafter, the transfer material P to which the toner image is transferred passes through the fixing unit 66 and is discharged from the discharge roller 69 to the outside of the apparatus.

On the other hand, the toner T (untransferred toner) remaining on the photosensitive drum 21 without being transferred to the transfer material P during the transfer process reaches a portion facing the cleaning unit 25 while remaining on the photosensitive drum 21. The untransferred toner on the photosensitive drum 21 is removed and collected by the cleaning unit 25.
Thereafter, the surface of the photosensitive drum 21 passes through a static elimination unit (not shown), and a series of image forming processes on the photosensitive drum 21 is completed.

Hereinafter, the configuration and operation of the developing device 23 will be described in detail.
Referring to FIG. 3, the developing device 23 includes developing rollers 23a1 and 23a2 as developer carriers, conveying screws 23b1 to 23b3 (auger screws) as conveying members, a doctor blade 23c as a developer regulating member, a carrier trap. It is composed of a collecting roller 23k, a scraper 23m, a discharge screw 23n, and the like. Further, in the developing device 23, three developer transport portions B1 to B3 that transport the developer G to form a circulation path are formed.

  The developing rollers 23a1 and 23a2 are configured such that a sleeve formed of a nonmagnetic material such as aluminum, brass, stainless steel, or conductive resin in a cylindrical shape is rotated clockwise by a rotation driving mechanism (not shown). . In the sleeves of the developing rollers 23a1 and 23a2, a magnet for forming a magnetic field is fixed so as to cause the developer G to rise on the peripheral surface of the sleeve. The carrier C in the developer G rises in a chain shape on the sleeve so as to follow the normal magnetic field lines emitted from the magnet. The charged toner T is attached to the carrier C that is spiked in a chain shape to form a magnetic brush. The magnetic brush is transferred in the same direction (clockwise) as the sleeve by the rotation of the sleeve.

The doctor blade 23c as a developer regulating member is installed on the upstream side of the developing area, and regulates the developer on the first developing roller 23a1 to an appropriate amount.
The doctor blade 23c (developer regulating member) is a plate-like member made of a nonmagnetic metal material such as SUS316 or SUSXM7 having a plate thickness of about 2 mm, and is screwed (held) to the case 23 of the developing device 23. ing.

Referring to FIG. 3, the three conveying screws 23 b 1 to 23 b 3 are each formed with a screw portion in a spiral shape on a shaft portion, and the developer G accommodated in the developing device 23 is disposed in the longitudinal direction (FIG. 2), while stirring and mixing.
The first conveying screw 23b1 as the first conveying member is disposed at a position facing the developing roller 23a1 in the first developer conveying portion B1, and conveys the developer G in the horizontal direction (see FIG. 4). In addition, the developer 23a is supplied onto the developing roller 23a1. In other words, the first developer transport unit B1 faces the developing roller 23a1 and supplies the developer G to the developing roller 23a1 while transporting the developer G in the longitudinal direction (the rotational axis direction of the developing roller 23a1).

The second transport screw 23b2 as the second transport member is installed in the second developer transport section B2. The second transport screw 23b2 is disposed below the first transport screw 23b1 and at a position facing the developing roller 23a2. Then, the developer G separated from the developing roller 23a2 (the developer G forcibly separated from the developing roller 23a2 by the agent separation pole after the developing step) is conveyed in the horizontal direction (indicated by a white arrow in FIG. 4). It is a left-hand conveyance.) In other words, the second developer transport unit B2 is disposed at a position below the first developer transport unit B1 and facing the developing roller 23a2, and the developer G detached from the developing roller 23a2 is disposed in the longitudinal direction. Transport in the direction.
The first transport screw 23b1 and the second transport screw 23b2 are arranged so that the rotation axis is substantially horizontal, like the developing rollers 23a1 and 23a2 and the photosensitive drum 21.

  The third transport screw 23b3 as the third transport member is installed in the third developer transport section B3. The third transport screw 23b3 is disposed obliquely with respect to the horizontal direction so as to linearly connect the downstream side of the transport path by the second transport screw 23b2 and the upstream side of the transport path by the first transport member 23b1. (See FIG. 4). The third transport screw 23b3 transports the developer G transported by the second transport screw 23b2 to the upstream side of the transport path by the first transport member 23b1, and from the downstream side of the transport path by the first transport screw 23b1. The developer G circulated through the drop path 23f is transported to the upstream side of the transport path by the first transport member 23b1 (the transport is obliquely upward to the right indicated by the white arrow in FIG. 4). In other words, the third developer transport unit B3 transports the developer G transported by the second developer transport unit B2 to the upstream side of the first developer transport unit B1, and also the first developer transport unit B1. The developer G that has reached the downstream side is transported to the upstream side of the first developer transport section B1.

A transport path (first developer transport section B1) by the first transport screw 23b1, a transport path by the second transport screw 23b2 (second developer transport section B2), and a transport path (first transport by the third transport screw 23b3). 3 developer transport section B3) is isolated from the wall.
Referring to FIG. 4, the downstream side of the second developer transport unit B2 and the upstream side of the third developer transport unit B3 communicate with each other via the first relay unit 23g. In addition, the downstream side of the third developer conveyance unit B3 and the upstream side of the first developer conveyance unit B1 are communicated with each other via the second relay unit 23h. In addition, the downstream side of the first developer transport unit B1 and the upstream side of the third developer transport unit B3 communicate with each other via a drop path 23f.

With such a configuration, a circulation path for circulating the developer G in the longitudinal direction in the developing device 23 is formed by the three developer conveying portions B1 to B3 (conveying screws 23b1 to 23b3). Here, when the developing device 23 is operated, the developer accommodated in the device flows in a state as indicated by the oblique lines in FIG. Referring to FIG. 4, in the first developer conveying section B1, the developer surface on the downstream side is lower than the upstream agent surface because part of the developer being conveyed is developed. This is because it is supplied to the roller 23a1. That is, the developer that has not been supplied to the developing roller 23a1 moves to the upstream side of the third developer conveying portion B3 via the dropping path 23f.
Note that a magnetic sensor 26 as a toner concentration sensor is installed in the third developer conveying portion B3. Then, based on the toner density information detected by the magnetic sensor 26, the developer G having a predetermined toner density is replenished from the powder replenishing device 80 (agent replenishing device) into the developing device 23. In the present embodiment, the toner concentration of the developer G in the developing device 23 is controlled to be 4 to 7% by weight.

4 and 5, a part of the developer G accommodated in the developing device 23 is discharged to the outside (agent storage container 70) on the wall portion of the first developer conveying portion B1. An agent discharge port 23d (discharge means) is provided. More specifically, the developer discharge port 23d is developed in such a manner that the developer G is replenished into the developing device 23 by the powder replenishing device 80 through the replenishing port 23r, and the amount of developer in the device increases and is conveyed to that position. When the agent surface (upper surface) of the agent exceeds a predetermined height, the excess developer G is discharged toward the agent storage container 70. That is, the excess developer G exceeds the lower portion of the agent discharge port 23d, is discharged from the agent discharge port 23d, and drops by gravity toward the agent storage container 70 via the discharge path 71. . As described above, the carrier deteriorated by being contaminated by the base resin or the external additive of the toner T is automatically discharged to the outside of the developing unit, so that deterioration of the image quality can be suppressed even over time.
Although not shown in FIGS. 2, 4, 5, etc., a discharge screw 23 n for conveying the developer discharged from the agent discharge port 23 d in the horizontal direction is installed in the discharge path 71. (See FIG. 3). The discharge screw 23n rotates in the clockwise direction in FIG.

Further, in the developer circulation path in the developing device 23, a part of the developer G is returned to the upstream side of the circulation path without passing through the position where the agent discharge port 23d (discharge means) is disposed. A bypass path is formed. Specifically, referring to FIG. 4 and FIG. 6, in the first developer transport unit B1, upstream of the agent discharge port 23d (a position relatively close to the agent discharge port 23d). An opening 23e is provided. The opening 23e serves as the inlet of the bypass path, and the outlet of the bypass path is disposed in the transport path (near the center in the longitudinal direction) by the third transport screw 23b3.
In this way, by providing a bypass path in the developer circulation path in the developing device 23, even if a wavy deviation occurs in the developer in the developing device, the amount of developer discharged from the agent discharge port 23d varies. Therefore, it is possible to suppress the problem that the developer exceeding the necessary amount is discharged from the developing device 23. In the present embodiment, the height of the lower portion of the opening 23e in the bypass path is higher than the height of the lower portion of the discharge port 23d in order to reliably prevent a problem that the developer is excessively discharged from the discharge port 23d. It is configured to increase by the height H1.

Here, referring to FIG. 3 (not shown in FIGS. 2, 4 to 6 and the like), in the present embodiment, below the second developing roller 23a2 (downstream in the rotational direction). The carrier collecting roller 23k is installed at a position facing the photosensitive drum 21. Further, a scraper 23m is installed at a position where it abuts on the carrier collecting roller 23k.
The carrier collecting roller 23k is a cylindrical body made of stainless steel or the like in which a magnet for forming a predetermined magnetic field is fixed, and the carrier that moves (flys) from the inside of the developing device 23 and adheres to the photosensitive drum 21. It is for collecting. The carrier collecting roller 23k is driven to rotate counterclockwise in FIG. Most of the carrier collected and carried by the carrier collecting roller 23k is transferred to the developing roller 23a2 at a position facing the second developing roller 23a2, and developed at the position of the developer separating pole of the developing roller 23a2. It separates from the roller 23a2 and is collected in the second developer conveying section B2. On the other hand, the carrier remaining and carried on the carrier collecting roller 23k without moving onto the developing roller 23a2 is mechanically scraped off by the scraper 23m and collected in the second developer conveying portion B2. In this way, by installing the carrier collecting roller 23k, the carrier adhering to the photosensitive drum 21 can be collected in the developing device 23, so that the occurrence of abnormal images (firefly images, whiteout images) is suppressed. In addition, the shortage of carriers in the developing device 23 is suppressed.

In the present embodiment, the outer diameters of the developing rollers 23a1 and 23a2 are 30 mm, the linear velocity on the outer peripheral surface of the developing rollers 23a1 and 23a2 is 748 mm / second, the outer diameter of the carrier collecting roller 23k is 16 mm, and the carrier collecting The linear velocity on the outer peripheral surface of the roller 23k is 10.6 mm / second, the process linear velocity (the linear velocity on the outer peripheral surface of the photosensitive drum 21 and the conveyance speed of the transfer material P) is 440 mm / second, Is set to about.
The carrier C used in the present embodiment has a particle size of 55 μm and a saturation magnetization of about 96 emu / g. Further, the toner T used in the present embodiment has a particle size of about 6.8 μm.

Hereinafter, the configuration and operation of the powder replenishing device 80 (agent replenishing device) provided with the shutter mechanism characteristic in the present embodiment will be described in detail with reference to FIGS.
As described above with reference to FIG. 2 and the like, the powder replenishing device 80 temporarily stores the developer G (powder) supplied from the agent cartridge 28 via the supply pipe 29, and the process cartridge This is an apparatus for appropriately supplying the developer G toward the twenty developing devices 23.
As shown in FIGS. 7 and 8, the powder replenishing device 80 includes a replenishing device main body 81 (case), shutter mechanisms 81a and 87, a pump 82, a stirring member 83, a replenishing screw 84, a piezoelectric sensor 85, and the like. Has been.

The replenishing device main body 81 (case) is formed of a resin material by mold molding, and a space for storing the developer G supplied from the agent cartridge 28 is formed therein. In the upper part of the replenishing device main body 81, the supply port communicating with the agent cartridge 28 through the supply pipe 29 and the suction and conveyance of the developer G from the agent cartridge 28 through the supply pipe 29 by pump action are enabled. A pump 82 is provided.
The agitating member 83 is a member in which a flexible member 83b is adhered to a rotating shaft 83a, and replenishes the developer G contained in the replenishing device main body 81 while agitating and mixing by rotating in a predetermined direction. While being conveyed toward the screw 84, the developer G is slidably brought into contact with the sensor surface of the piezoelectric sensor 85 to prevent the developer G from sticking to the sensor surface.
The replenishing screw 84 has a screw portion spirally formed on the shaft portion, and is longitudinally below the replenishing device main body 81 (the left-right direction in FIG. 8 and the vertical direction in FIG. 7). )) Is installed inside a supply pipe formed to extend. The supply screw 84 is rotationally driven together with the agitating member 83 by a drive motor (not shown), and conveys the developer G stored in the supply device main body 81 in the longitudinal direction toward the discharge port 81a1 (right side in FIG. 8). From left to right.) In this way, the developer G transported to the position of the discharge port 81a1 falls by its own weight and is replenished to the developing device 23 (first developer transport unit B1) via the replenishment port 23r communicating with the discharge port 81a1. Will be. Note that such a replenishment operation by the replenishment screw 84 is performed based on the detection result of the magnetic sensor 26 of the developing device 23 as described above with reference to FIG.
The piezoelectric sensor 85 (agent detection means) is for detecting whether the developer G in the replenishing device body 81 is stored up to that position (height). When the piezoelectric sensor 85 detects that there is no developer G at that position, the pump 82 is driven and the developer G is replenished from the agent cartridge 28 toward the replenishing device main body 81.

Here, referring to FIG. 8 and the like, the powder supply device 80 according to the present embodiment opens and closes the discharge port 81a1 in conjunction with the attaching / detaching operation of the developing device 23 (process cartridge 20) with respect to the image forming apparatus main body 1. Shutter mechanisms 81a and 87 are provided.
Specifically, in the shutter mechanism, a shutter member 87 that opens and closes a discharge port 81a1 (discharge path) through which the developer G (powder) is discharged, and the shutter member 87 are in the open / close direction (the horizontal direction in FIG. 8). ) And a shutter holding portion 81a for guiding the shutter member 87 while holding it.
The shutter member 87 is a substantially plate-like member made of a resin material, and a driven portion 87a is formed on one end side in the opening / closing direction. The driven portion 87a is formed so as to protrude downward from the surface (main surface) of the shutter member 87, and is a projection 23j of the developing device 23 (process cartridge 20) (in the longitudinal direction from the case of the developing device 23). It is formed so that it may contact | abut. Further, a boss portion for holding one end side of the compression spring 89 (biasing member) is formed in the driven portion 87a. Note that the other end of the compression spring 89 is held by a boss formed in a protruding portion that protrudes downward from the supply device main body 81.

With such a configuration, when the developing device 23 (process cartridge 20) is not attached to the image forming apparatus main body 1, the shutter member 87 is guided to the shutter holding portion 81 a by the urging force of the compression spring 89 and the shutter member 87 is discharged. It will move in the direction (closing direction) which closes 81a1 (it is the movement to the left of FIG. 8). In this way, in the image forming apparatus main body 1 in which the discharge port 81a1 is closed by the shutter member 87 and the developing device 23 is not installed, the developer G is discharged from the discharge port 81a1 of the powder supply device 80 (replenishment device main body 81). It is possible to prevent the problem of leakage.
In contrast, when the developing device 23 (process cartridge 20) is attached to the image forming apparatus main body 1 while moving in the direction of the white arrow in FIG. 8, the shutter member 87 (the pushed portion 87a) is compressed by a compression spring. It is pushed by the developing device 23 (projection 23j) so as to resist the urging force of 89, and is guided by the shutter holding portion 81a to move the shutter member 87 in a direction (opening direction) for opening the discharge port 81a1. (Move to the right in FIG. 8). In this way, the discharge port 81a1 is opened by the shutter member 87, and the discharge port 81a1 of the powder supply device 80 and the supply port 23r of the developing device 23 communicate with each other, so that toner supply from the powder supply device 80 to the developing device 23 is performed. Is possible.
A sealant made of foamed polyurethane or the like is stuck around the replenishing port 23r of the developing device 23, and development is performed from around the replenishing port 23r in a state where the powder replenishing device 80 and the developing device 23 are in communication. The trouble that the agent G leaks is prevented. Further, the tip of the protrusion 23j of the developing device 23 is formed in a substantially hemispherical shape so that the contact resistance with the shutter member 87 (the pushed portion 87a) is reduced.

  Here, the shutter holding portion 81a is formed in a substantially box shape so as to cover the shutter member 87 in a part of the replenishing device main body 81, and is formed of a resin material by die molding. Referring to FIG. 9, a discharge port 81 a 1 is formed in the shutter holding portion 81 a so as to face the surface (main surface) of the shutter member 87, and is a width direction of the shutter member 87 (a direction orthogonal to the opening / closing direction). )) Is formed so as to face both end portions (both side surfaces) of the wall portion 81a2 (inner wall portion). Further, the shutter holding portion 81a is formed with a substantially rectangular opening 81a3 for enabling the shutter member 87 to move in the opening / closing direction (see also FIG. 10B). FIG. 9 is a view of the shutter mechanism of FIG.

In the present embodiment, as shown in FIGS. 9A and 9B, the shutter member 87 is located relative to the wall portion 81a2 of the shutter holding portion 81a in the plane where the shutter member 87 is opened and closed. It is formed to move in a direction in which the discharge port 81a1 is opened (in the direction of the white arrow in FIG. 9) in a relatively inclined state.
Specifically, the shutter holding portion 81a has a predetermined wall portion 81a2 with respect to the opening / closing direction of the shutter member 87 (the direction indicated by the one-dot chain line in FIG. 9) in the plane where the shutter member 87 is opened / closed. It is formed so as to be inclined by an inclination angle α.

With such a configuration, the shutter member 87 is accommodated in the shutter holding portion 81a so as to be along the inclined wall portion 81a2 to some extent at the time of closing shown in FIG. 9A, and the discharge port 81a1 is closed by the shutter member 87. Will be.
On the other hand, at the time of opening shown in FIG. 9B, the shutter member 87 is pushed by the developing device 23 (projecting portion 23j) and does not move in the opening direction along the inclination of the wall portion 81a2. Without moving to the opening 81a3, it moves along the opening direction indicated by the one-dot chain line (inclined relative to the wall 81a2 by an angle α and moves straight in the direction perpendicular to the plane of FIG. 7). Then, the discharge port 81a1 is opened. At this time, in the portion surrounded by the broken line in FIG. 9B, the shutter member 87 comes into close contact with the wall portion 81a2 (shutter holding portion 81a). The problem that the developer G (particularly, toner T) scatters from the space 81a (replenisher main body 81) is reduced. That is, in the state where the powder replenishing device 80 and the developing device 23 communicate with each other, the hermeticity between the shutter member 87 and the shutter holding portion 81a (replenishing device main body 81) is improved. Therefore, the problem that the toner T in the developer G replenished toward the toner and the toner T rising from the developing device 23 scatters to the outside is reduced. Further, the close contact between the shutter member 87 and the shutter holding portion 81a at the time of opening is surely ensured even if the draft angle by the mold molding is formed on the wall portion 81a2.
In particular, in the developing device 23 according to the present embodiment, the replenishing port 23r is installed on the downstream side of the first developer conveying portion B1 (the portion where the internal pressure increases due to the flow of the developer G), and the internal pressure is increased. Since the toner T easily rises so as to flow backward from the replenishing port 23r to the powder replenishing device 80 due to the rise, it is useful to improve the sealing performance in the shutter mechanisms 81a and 87 as described above.

  Here, with reference to FIG. 9A, in the present embodiment, the distance N2 between both ends in the width direction of the shutter member 87 is shorter than the distance N1 between the two wall portions 82a2 facing each other in the shutter holding portion 81a. (N1> N2). As a result, the shutter member 87 is smoothly opened and closed without significant elastic deformation.

In the present embodiment, the protrusion 23j of the developing device 23 is formed only on one end side in the width direction, and when the shutter member 87 is opened, the width and one end side in the width direction of the shutter member 87 (the pushed portion 87a). Instead of pushing the other end in the direction equally, it is also possible to push only one end in the width direction of the shutter member 87 (the pushed portion 87a) (as indicated by the black arrow in FIG. 9). The push at the position shown.)
Accordingly, the shutter member 87 can be easily moved straight in the opening direction without being along the inclined direction of the inclined wall portion 81a2, and the shutter member 87 can be easily adhered to the wall portion 81a2 when opened.

As shown in FIG. 10, in the present embodiment, the seal member 88 having elasticity on the surface of the shutter member 87 (the surface facing the surface where the discharge port 81a1 is formed in the shutter holding portion 81a). (For example, a thin low friction resistance material made of polyethylene terephthalate or the like is attached to the surface of an elastic material such as polyurethane foam) is preferably attached. By installing the seal member 88, the problem that the developer G leaks from between the shutter member 87 and the discharge port 81a1 when closed is surely reduced.
As shown in FIG. 10, the seal member 88 is a portion close to the wall portion 81 a 2 when the shutter member 87 moves in the opening direction (a portion surrounded by a broken line in FIG. 10). It is preferable to be formed so as to extend to the position of the end portion in the width direction or to the outer position beyond that position.
With this configuration, when the shutter member 87 is in close contact with the inclined wall portion 81a2 when opened, the wide portion of the seal member 88 (a portion formed wide in the width direction) is formed on the close wall portion 81a2. ) Is in pressure contact with each other, the sealing performance of that portion is further improved.

In the present embodiment, the wall portion 81a2 of the shutter holding portion 81a is formed to be inclined so that the shutter member 87 moves in the opening direction in a state where the shutter member 87 is inclined relative to the wall portion 81a2. did.
On the other hand, as shown in FIG. 11, the wall portion 81a2 of the shutter holding portion 81a is formed straight in the longitudinal direction without being inclined, and only one end side in the width direction of the shutter member 87 when opened is the developing device 23 ( By pushing the projection 23j), the shutter member 87 can be moved in the opening direction in a state where the shutter member 87 is relatively inclined with respect to the wall 81a2. In this case, in order to reliably perform such an opening operation in the oblique direction of the shutter member 87, it is preferable that the hole shape of the opening 81a3 is formed obliquely in accordance with the opening direction of the shutter member 87.
Even in this configuration, the shutter member 87 is in close contact with the wall portion 81a2 (shutter holding portion 81a) in the portion surrounded by the broken line in FIG. In this case, the problem that the developer G (particularly, toner T) is scattered from between the shutter member 87 and the shutter holding portion 81a (replenisher main body 81) is reduced.

  As described above, in the present embodiment, since the shutter member 87 moves in the opening direction in a state in which the shutter member 87 is inclined relative to the wall portion 81a2 of the shutter holding portion 81a, the shutter member 87 and the shutter holding portion 81a It is possible to reduce a problem that a gap is generated between the two and the developer G (powder) is scattered.

In the present embodiment, the present invention is applied to the shutter mechanism that opens and closes the discharge port 81a1 for discharging the two-component developer G (toner T and carrier C) as powder, but other powder is discharged. The present invention can also be applied to a shutter mechanism that opens and closes a discharge port. In particular, it is installed in a powder replenishing device (toner replenishing device) for replenishing a one-component developer (a developer formed only with toner T) toward a two-component developing type or a one-component developing type developing device. The present invention can also be applied to the shutter mechanism.
Even in this case, the same effect as that of the present embodiment can be obtained.

  Further, in the present embodiment, the present invention is applied to an image forming apparatus in which a part of the image forming unit is configured by the process cartridge 20. However, the application of the present invention is not limited to this, and the present invention can naturally be applied to an image forming apparatus in which the image forming unit is not formed into a process cartridge. Specifically, the present invention can naturally be applied even when the developing device 23 is configured as a unit that is detachably attached to the image forming apparatus main body.

  It should be noted that the present invention is not limited to the present embodiment, and it is obvious that the present embodiment can be modified as appropriate within the scope of the technical idea of the present invention, other than suggested in the present embodiment. is there. In addition, the number, position, shape, and the like of the constituent members are not limited to the present embodiment, and the number, position, shape, and the like suitable for implementing the present invention can be achieved.

  In the present application, the “process cartridge” refers to a charging unit that charges the image carrier, a developing unit (developing device) that develops a latent image formed on the image carrier, and a cleaning on the image carrier. It is defined as a unit in which at least one of the cleaning units and the image carrier are integrated and installed detachably with respect to the image forming apparatus main body.

1 image forming apparatus body (apparatus body),
20, 20Y, 20C, 20M, 20BK Process cartridge,
21 Photosensitive drum (image carrier),
23 Developing device (developing part),
23a1, 23a2 developing roller (developer carrier),
23c Doctor blade (developer regulating member),
23j protrusion (pushing part),
23r supply port,
80 Powder replenishing device (agent replenishing device),
81 supply device body,
81a shutter holding part,
81a1 outlet,
81a2 wall (inner wall),
81a3 opening,
87 shutter member,
87a driven part,
88 seal member,
89 Compression spring (biasing member),
G developer (two-component developer, powder), T toner, C carrier.

JP 2009-86219 A JP 2009-86220 A

Claims (7)

A shutter member that opens and closes a discharge port through which the powder is discharged;
The discharge port is formed to face the surface of the shutter member, and wall portions are formed to face both ends of the shutter member in the width direction so that the shutter member moves in the opening / closing direction. A shutter holding portion for guiding the shutter member in a held state;
With
The shutter member is formed to move in a direction to open the discharge port in a state in which the shutter member is relatively inclined with respect to the wall portion of the shutter holding portion within a surface where the shutter member is opened and closed .
The shutter mechanism , wherein the shutter holding portion is formed so that the wall portion is inclined with respect to an opening / closing direction of the shutter member in a plane where the shutter member is opened / closed . The shutter holding portion includes an opening for enabling movement of the shutter member in the opening / closing direction,
2. The shutter mechanism according to claim 1, wherein a distance between both end portions in the width direction of the shutter member is shorter than a distance between two wall portions facing each other in the shutter holding portion. A shutter member that opens and closes a discharge port through which the powder is discharged;
The discharge port is formed to face the surface of the shutter member, and wall portions are formed to face both ends of the shutter member in the width direction so that the shutter member moves in the opening / closing direction. A shutter holding portion for guiding the shutter member in a held state;
With
The shutter member is formed to move in a direction to open the discharge port in a state in which the shutter member is relatively inclined with respect to the wall portion of the shutter holding portion within a surface where the shutter member is opened and closed.
The shutter holding portion includes an opening for enabling movement of the shutter member in the opening / closing direction,
A shutter mechanism, wherein a distance between both end portions in the width direction of the shutter member is shorter than a distance between two wall portions facing each other in the shutter holding portion. The shutter member is moved in a direction in which the discharge port is opened in a state where the shutter member is inclined with respect to the wall portion of the shutter holding portion when one end side in the width direction is pushed. The shutter mechanism according to claim 3. A sealing member having elasticity is installed on the surface of the shutter member,
When the seal member moves in a direction to open the discharge port, a portion close to the wall portion extends to a position of an end portion in the width direction of the shutter member or an outer position beyond the position. The shutter mechanism according to any one of claims 1 to 4, wherein the shutter mechanism is formed. The powder is a two-component developer or a one-component developer,
2. A powder replenishing device that contains a two-component developer or a one-component developer and replenishes powder toward a developing device that develops a latent image formed on an image carrier. The shutter mechanism according to any one of claims 1 to 5.   An image forming apparatus comprising the powder supply device according to claim 6, the developing device, and the image carrier.

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